Advertisement

Peaceful basking sharks can leap just as powerfully as great whites

A basking shark shows off its leaping skills

Youen Jacob

By Yvaine Ye

Gliding through the ocean and feeding on tiny animals, the basking shark seems far more peaceful than its ferocious relative the great white shark. But it turns out languid basking sharks can swim as fast and jump out of the water as high as great whites if they so choose.

Great white sharks are known to jump out of the water – or breach – to capture agile seals and otters. By comparison, basking sharks eat mostly zooplankton that drift into their 1 metre wide megamouths. They are also much larger than great whites, so it’s a mystery why they would expand effort on breaching. But for some reason, they do.

In an attempt to understand the unusual behaviour, Jonathan Houghton at Queen’s University in Belfast, and his colleagues placed a monitoring device on an 8-metre-long, 2.7-tonne basking shark swimming near Ireland and captured a breaching event after 3 hours. Bren Whelan, another member of the team, also filmed the breaching behaviours of 20 basking sharks from the shore.

The footage showed giant basking sharks leaping near vertically to about 1.2 metres above the water surface. Houghton estimates the sharks must have accelerated to a speed of 18 kilometres per hour for breaching – the same speed reached by white sharks.

The entire breaching event, from bursting to recovery, would cost an 8-metre-long basking shark 45 to 51 kilocalories – a greater energy expenditure than white sharks incur when they breach. But because basking sharks are almost twice the size of great whites, the researchers concluded that the two species’ energy spent per kilogram of body weight are comparable.

“The similar energy cost between basking and white sharks is surprising to me,” says David Sims at the Marine Biology Association in Plymouth, UK. He points out that great white and basking sharks have very different cardiovascular capacities for their divergent lifestyles. Great white sharks are relatively warm-bodied and known to chase down fast-swimming tuna, whereas basking sharks have colder bodies and swim slowly.

The analysis has revealed some more details about how basking sharks breach, but why they do it still remains elusive. “At present, it’s a mystery,” says Sims.